| (19) |
 |
|
(11) |
EP 0 311 309 A3 |
| (12) |
EUROPEAN PATENT APPLICATION |
| (88) |
Date of publication A3: |
|
06.02.1991 Bulletin 1991/06 |
| (43) |
Date of publication A2: |
|
12.04.1989 Bulletin 1989/15 |
| (22) |
Date of filing: 30.09.1988 |
|
| (51) |
International Patent Classification (IPC)4: H01L 21/76 |
|
| (84) |
Designated Contracting States: |
|
DE ES GB |
| (30) |
Priority: |
09.10.1987 US 107081
|
| (71) |
Applicant: AT&T Corp. |
|
New York, NY 10013-2412 (US) |
|
| (72) |
Inventors: |
|
- Easter, William Graham
Reading
Pennsylvania 19604 (US)
- Leffel, Daniel David
Boyertown
Pennsylvania 19512 (US)
|
| (74) |
Representative: Watts, Christopher Malcolm Kelway, Dr. et al |
|
AT&T (UK) LTD.
AT&T Intellectual Property Division
5 Mornington Road
Woodford Green
Essex IG8 OTU
Woodford Green
Essex IG8 OTU (GB) |
|
| |
|
| (54) |
Method of forming semiconductor device structures including dielectrically isolated
tubs |
(57) A method has been developed for altering the resistivity value and/or conductivity
type of selected tubs in a dielectrically isolated (DI) wafer. Subsequent to the formation
of the conventional tub structure, the wafer is covered with a patterning layer (20)
which is etched to expose the selected tubs. Material is then removed from these tubs
by etching and material (24, 26) having a new resistivity value and/or conductivity
type is grown in the empty tub regions.